1. Field of the Invention
The present invention generally relates to a high voltage semiconductor device, and more particularly to a high voltage semiconductor device having a high breakdown voltage and a fabrication method thereof.
2. Description of the Related Art
Generally, a high voltage transistor has a property of driving a signal processing part which processes an electrical signal and a mechanical part which operates according to a processing result of the electrical signal, the property being different from most semiconductor devices. In order to effectively drive the mechanical part, high power(current x voltage) should be provided. In most cases, a large current is provided in the application of high power. There exist, however, many cases needing a high voltage difference. In such cases, when the driving voltage approaches 100 V, a high breakdown voltage should be ensured in order to protect the high voltage semiconductor device. A conventional high voltage semiconductor device essentially requires an optimized drain structure. In a conventional case, a potential absorption method using a doping profile is used. In further detail, resistance difference due to a concentration difference between n.sup.+ /n.sup.- doped regions, and dispersion of electric field are used. As a result, the area of drain region increases with the increase in the driving voltage. Therefore, when current above a certain level, is abruptly introduced to a drain region having a resistance which allows only a current below the certain level to flow. As a result, there is an increased probability of breakdown due to joule heat, of snapback breakdown due to hot carriers.